What Is BMI, And Why Is It Important?
What Is BMI, And Why Is It Important?
28 Aug 2018

Body Mass Index - or BMI – is a calculation of body weight in relation to height which is used to determine your body fat.

For most individuals, BMI provides a good general guideline as to your ideal weight and can also be used to help assess your general health and whether you are at risk of developing chronic conditions or illnesses.

A very high BMI, for example, would mean that you are overweight or obese and therefore more likely to suffer from diabetes, heart disease and other obesity-related health problems. Research has shown a particularly strong link between a high BMI and type two diabetes.

A body mass index that is too low could indicate malnourishment or illness, or simply that you are not taking in enough calories.

So how do you find out what your BMI is, what is a healthy range and why do some people say that BMI isn’t an accurate measure of health? Here’s our handy guide to Body Mass Index

How is BMI calculated?

To calculate your BMI manually, use the following steps.

1. divide your weight in kilograms (e.g. 50kg) by your height in metres (e.g 1.6m).

- 50 ÷ 1.6 = 31.25

  1. then divide the answer by your height again to get your BMI

- 31.25 ÷ 1.6 = 19.53

BMI = 19.53


An easier way to do this is to use a BMI calculator where you can input your weight and height and let the calculator do all the hard work for you! The MiWayLife BMI calculator will also tell you whether your BMI is low, normal or high.


What is a healthy BMI?

BMI tends to work on ranges rather than exact figures. Within the healthcare professions, generally accepted ranges of low, average and high BMI are as follows:

  • Below 18.5: Underweight
  • Between 18.5-25: Normal weight
  • Between 25-30: Overweight
  • Over 30: Obese


When BMI doesn’t work

The body mass index has received criticism as a measurement of body fat. This is because for some individuals, a BMI calculation can give inaccurate information about health, fitness and obesity. Very muscular people such as weightlifters or certain athletes for example, may find that their BMI is high despite being fit, healthy and having a low body fat percentage in reality. This is because muscle weights more than fat. Women also have a naturally higher body fat percentage than men so even with a lower BMI, could still have a relatively high body fat percentage.

However, for most individuals BMI is a useful guideline as to a healthy weight and your general health – it just isn’t the only useful guideline and so it is usually used in conjunction with other measures.


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